The active transport of sugars in renal cortical cells, and its relationship to metabolism will be investigated: 1. The properties of the transport system specific for glucose, 2-deoxy-glucose, and mannose will be studied in more detail: a) by investigating the effect of phlorizin, phloretin and 2-deoxy-glucosylphloretine on the cellular metabolism of the above sugars; b) by studying the specificity of the kinase(s) and phosphortases involved in the intracellular metabolism of these sugars. (in part in cooperation with Dr. Bertram Sacktor NIA, Baltimore); c) By determining the transport specificity in vesicles of basolateral membranes (in cooperation with Drs. R. Kinne and H. Murer, Max Planck Inst., Frankfurt); d) by clarifying the interaction of (H3) 2-deoxy-glucosylphloretin with membrane preparations. 2. The specificity of the galactose-2-deoxy-galactose transport system will be studied using sugar analogs to be prepared in this lab. These sugars will also be tested by the double-microperfusion technique of renal tubules (cooperation with Dr. K.J. Ullrich, Max. Planck Inst. Frankfurt). 3. Using teased flounder tubules a study of the role of -SH groups in the transport sites for sugars will be concluded. BIBLIOGRAPHIC REFERENCES: Renal Clearance of Sugars by the Winter Flounder, Pseudopleuronectes americanus, John B. Pritchard, Margaret A. Cauthen, Pamela Goldstein, Elizabeth McAvoy, and Arnost Kleinzeller, The Bulletin, Mt. Desert Island Biological Laboratory, Vol. 14, 1974. Specificity of Sugar Transport Across Brush Border of the Rat Proximal Tubule, Ullrich, K.J., Fromter, E., Hinton, B.J. Rumrich, G. Klenzeller, Arnost. In: Biochemical Aspects of Kidney Function. U. Schmidt and U.C. Dubach (eds.) Verl. Hans Huber, Bern, Stuttgart, Wien, 1976.